This invention relates generally to surface temperature measuring devices. More particularly, the present invention relates to surface temperature measuring devices that are placed in contact with the surface whose temperature is to be measured.
Conventional surface temperature measuring devices have often included a contact plate which is placed in contact with the object surface. The size of such contact plates was determined by a number of factors. On the one hand, the contact plate must not be so small that small, localized deposits on the object surface or the contact plate disproportionately affect the heat flow to the contact surface. Small contact plates are mechanically less robust and easily bend when the temperature measuring device is subjected to a relatively high bearing pressure. On the other hand, if the contact plate is formed to be relatively large, the measurements require more time, as a result of the greater thermal capacity of the plate. It is also a disadvantage of large contact plates that sufficiently large plane areas on the object are often not available. For measuring the surface temperature of cylindrical objects, such as pipes, a separate contact plate or measuring device is required for each diameter of pipe.
Hand-held devices having contact plates are especially unreliable and inaccurate, in part because the contact plate is not placed sufficiently flush on the object surface. Over the time period typically required to measure the temperature, the operator""s hand typically cannot be held still or begins to tremble, as a result of continual body movements. This causes the contact plate to tilt relative to the object surface. Pressing the contact plate more firmly against the surface in an effort to provide better contact generally only serves to increase trembling of the operator""s hand. The trembling movements of the hand are of many different kinds and of large dynamic range, such that they cannot be automatically countered in the signal processing portion of the device.
Briefly stated, the invention in a preferred form is a probe for measuring the surface temperature of a pipe which comprises an active clamp assembly and a passive clamp assembly, with the first end of the passive clamp assembly pivotally mounted to the first end of the active clamp assembly. The active clamp assembly includes a first end portion forming a lower handle and a second end portion forming an upper jaw. A clamp temperature sensor assembly is carried in the upper jaw and an electronics module is carried in the lower handle. The electronics module is in communication with the clamp temperature sensor assembly and has a display panel. The passive clamp assembly includes a first end portion forming an upper handle and a second end portion forming a lower jaw. A spring biases the upper handle away from lower handle. The surface temperature of the pipe is sensed by squeezing the upper and lower handles together opening a gap between the upper and lower jaws, inserting the pipe into the gap, and releasing the upper and lower handles. The spring urges the upper jaw toward the lower jaw to clamp the pipe therebetween and the clamp temperature sensor senses the surface temperature of the pipe.
The upper jaw has a clamping surface adapted for engaging the surface of the pipe. The clamp temperature sensor assembly comprises a sensor subassembly and a resilient underlayment composed of thermally insulating material. A first surface of the resilient underlayment is mounted within a recess of the clamping surface and the second surface is mounted to the sensor subassembly such that the sensor subassembly extends a predetermined distance from the clamping surface of the upper jaw. The sensor subassembly includes a temperature sensor mounted between inner and outer heat transfer elements, where each of the heat transfer elements are composed of a thin foil of highly conductive metal.
Preferably, the active clamp assembly also includes a spike temperature probe assembly including a rotary hinge rotatably mounted within the lower handle and a spike temperature probe having a pointed distal end portion and a proximal end portion mounted to the rotary hinge. The spike temperature probe is rotatable between an in-service position and a stowed position. The electronics module has a switch for connecting the spike temperature probe and disconnecting the clamp temperature sensor subassembly when the spike temperature probe is in the in-service position and connecting the clamp temperature sensor subassembly and disconnecting the spike temperature probe when the spike temperature probe is not in the in-service position.
A latch holds the spike temperature probe at the in-service position whenever the spike temperature probe is in service and within a recess of the lower handle when the spike temperature probe is not in service. The latch comprises first and second circumferentially spaced detents in the rim of the rotary hinge, a ball, and a spring. The spring biases the ball into the first detent when the spike temperature probe is positioned within the recess of the lower handle and biases the ball into the second detent when the spike temperature probe is positioned at the in-service position.
It is an object of the invention to provide a new and improved probe for measuring the surface temperature of a pipe.
It is also an object of the invention to provide a probe which is temporarily installed by hand to measure the surface temperature of a pipe, but which holds itself in place on the pipe surface.
Other objects and advantages of the invention will become apparent from the drawings and specification.